Xamarin Forms convert color name to Xamarin.Forms.Color

As I said in comments, although you do not remove the switch, if you can make a converter that facilitates your use in xaml with bindings.

First you create a class of the converter, which is called StringToColorConverter, for example:

using System;
using System.Globalization;
using Xamarin.Forms;

namespace Proyecto.Converters
{
    public class StringToColorConverter : IValueConverter
    {
        public object Convert(object value, Type targetType, object parameter, CultureInfo culture)
        {
            Color colorDevolver = Color.Transparent;
            if (value is string)
            {
                string color = (string)value;
                switch (color)
                {
                    case "Accent":
                        colorDevolver = Color.Accent;
                        break;
                    case "AliceBlue":
                        colorDevolver = Color.AliceBlue;
                        break;
                    case "Azure":
                        colorDevolver = Color.Azure;
                        break;
                    case "Bisque":
                        colorDevolver = Color.Bisque;
                        break;
                    case "Black":
                        colorDevolver = Color.Black;
                        break;
                    case "Blue":
                        colorDevolver = Color.Blue;
                        break;
                    case "BlueViolet":
                        colorDevolver = Color.BlueViolet;
                        break;
                    case "BurlyWood":
                        colorDevolver = Color.BurlyWood;
                        break;
                    case "Cyan":
                        colorDevolver = Color.Cyan;
                        break;
                    case "DarkGray":
                        colorDevolver = Color.DarkGray;
                        break;
                    case "DarkKhaki":
                        colorDevolver = Color.DarkKhaki;
                        break;
                    case "DarkOrange":
                        colorDevolver = Color.DarkOrange;
                        break;
                    case "DarkRed":
                        colorDevolver = Color.DarkRed;
                        break;
                    case "DarkSeaGreen":
                        colorDevolver = Color.DarkSeaGreen;
                        break;
                    case "DarkViolet":
                        colorDevolver = Color.DarkViolet;
                        break;
                    case "DimGray":
                        colorDevolver = Color.DimGray;
                        break;
                    case "DodgerBlue":
                        colorDevolver = Color.DodgerBlue;
                        break;
                    case "FloralWhite":
                        colorDevolver = Color.FloralWhite;
                        break;
                    case "Fuchsia":
                        colorDevolver = Color.Fuchsia;
                        break;
                    case "Gainsboro":
                        colorDevolver = Color.Gainsboro;
                        break;
                    case "GhostWhite":
                        colorDevolver = Color.GhostWhite;
                        break;
                    case "Gray":
                        colorDevolver = Color.Gray;
                        break;
                    case "Honeydew":
                        colorDevolver = Color.Honeydew;
                        break;
                    case "HotPink":
                        colorDevolver = Color.HotPink;
                        break;
                    case "Khaki":
                        colorDevolver = Color.Khaki;
                        break;
                    case "Lavender":
                        colorDevolver = Color.Lavender;
                        break;
                    case "LavenderBlush":
                        colorDevolver = Color.LavenderBlush;
                        break;
                    case "LemonChiffon":
                        colorDevolver = Color.LemonChiffon;
                        break;
                    case "LightBlue":
                        colorDevolver = Color.LightBlue;
                        break;
                    case "LightCyan":
                        colorDevolver = Color.LightCyan;
                        break;
                    case "LightCoral":
                        colorDevolver = Color.LightCoral;
                        break;
                    case "LightGoldenrodYellow":
                        colorDevolver = Color.LightGoldenrodYellow;
                        break;
                    case "LightGray":
                        colorDevolver = Color.LightGray;
                        break;
                    case "LightGreen":
                        colorDevolver = Color.LightGreen;
                        break;
                    case "LightSteelBlue":
                        colorDevolver = Color.LightSteelBlue;
                        break;
                    case "Lime":
                        colorDevolver = Color.Lime;
                        break;
                    case "MistyRose":
                        colorDevolver = Color.MistyRose;
                        break;
                    case "Moccasin":
                        colorDevolver = Color.Moccasin;
                        break;
                    case "NavajoWhite":
                        colorDevolver = Color.NavajoWhite;
                        break;
                    case "OliveDrab":
                        colorDevolver = Color.OliveDrab;
                        break;
                    case "Orange":
                        colorDevolver = Color.Orange;
                        break;
                    case "PaleGoldenrod":
                        colorDevolver = Color.PaleGoldenrod;
                        break;
                    case "PeachPuff":
                        colorDevolver = Color.PeachPuff;
                        break;
                    case "Pink":
                        colorDevolver = Color.Pink;
                        break;
                    case "Red":
                        colorDevolver = Color.Red;
                        break;
                    case "RoyalBlue":
                        colorDevolver = Color.RoyalBlue;
                        break;
                    case "Silver":
                        colorDevolver = Color.Silver;
                        break;
                    case "SpringGreen":
                        colorDevolver = Color.SpringGreen;
                        break;
                    case "Teal":
                        colorDevolver = Color.Teal;
                        break;
                    case "Thistle":
                        colorDevolver = Color.Thistle;
                        break;
                    case "Transparent":
                        colorDevolver = Color.Transparent;
                        break;
                    case "Violet":
                        colorDevolver = Color.Violet;
                        break;
                    case "Wheat":
                        colorDevolver = Color.Wheat;
                        break;
                    case "White":
                        colorDevolver = Color.White;
                        break;
                    case "WhiteSmoke":
                        colorDevolver = Color.WhiteSmoke;
                        break;
                    case "Yellow":
                        colorDevolver = Color.Yellow;
                        break;
                    case "InactiveBorder":
                        colorDevolver = Color.White;
                        break;
                    default:
                        colorDevolver = Color.Transparent;
                        break;
                }
            }
            return colorDevolver;
        }

        public object ConvertBack(object value, Type targetType, object parameter, CultureInfo culture)
        {
            throw new NotImplementedException();
        }
    }
}

Then you have to declare it, as I usually use the converters in more than one place I declare them in app.xaml like this:

   <Application.Resources>
        <ResourceDictionary>  
        <!--  CONVERTERS  -->
            <converters:StringToColorConverter x:Key="StringToColorConverter"/>
        </ResourceDictionary>
    </Application.Resources>

Once done, you can use it anywhere. Imagine for example that you have a button.

 <Button  
        BackgroundColor="{Binding Color, Converter={StaticResource StringToColorConverter}}"                 
        HorizontalOptions="FillAndExpand"
        Margin="50,0,50,20" /> 

If the viewmodel has the property Color with the string of the text, the button will automatically know which color the background has to be painted.