A simple in-editor visualizer for the Colors class generated by Blobinet.

ColorsBrowser.cs

using System;
using System.Collections.Generic;
using System.Reflection;
using UnityEditor;
using UnityEngine;

/// <summary>
/// Simple browser for the Colors class
/// available @ https://gist.github.com/Blobinet/d37f3bc259a43bfbfecec7dd5e376354
/// </summary>

public class ColorsBrowser : EditorWindow
{
	//public static ColorsBrowser I { get { return GetWindow<ColorsBrowser>(); } }

	Dictionary<string, Color> color_dict;
	List<string> colors_list;

	int pageNum = 0;
	int pageMax = 0;
	int colorsPerRow = 4;
	int rowsPerPage = 10;
	int colorsPerPage;
	int blockWidth = 180;
	int blockHeight = 40;


	[MenuItem("Window/BadCoyote/Colors Browser %&#c")]
	public static void ShowWindow()
	{
		EditorWindow.GetWindow(typeof(ColorsBrowser));

		var win = GetWindow(typeof(ColorsBrowser));
		win.minSize = new Vector2(900, 900);

	}

	void OnEnable()
	{
		Initialize();
	}

	void Initialize()
	{
		color_dict = new Dictionary<string, Color>();
		colors_list = new List<string>();

		int iters = 0;

		Type type = typeof(Colors);
		foreach (var p in type.GetFields(BindingFlags.Public|BindingFlags.Static))
		{
			var n = p.Name;

			var v = p.GetValue(null);

			color_dict[n.ToString()] = (Color)v;
			colors_list.Add(n.ToString());
			iters++;
		}

		colorsPerPage = colorsPerRow * rowsPerPage;
		pageMax = colors_list.Count / colorsPerPage;
	}


	void OnGUI()
	{
		if (color_dict.Count < 1 || colors_list.Count < 1)
		{
			return;
		}

		EditorGUILayout.Space();
		EditorGUILayout.BeginHorizontal();
		EditorGUILayout.LabelField("", GUILayout.Width(160));

		if (GUILayout.Button("Page " + pageNum, GUILayout.Width(200), GUILayout.Height(40)))
		{
			// Non-functional button, just for displaying the current page number.
		}

		EditorGUILayout.LabelField("", GUILayout.Width(100));

		if (GUILayout.Button("Home\n<<", GUILayout.Width(60), GUILayout.Height(40)))
		{
			if (pageNum != 0)
			{
				pageNum = 0;
				Refresh();
			}
		}

		if (GUILayout.Button("Prev\n<", GUILayout.Width(60), GUILayout.Height(40)))
		{
			if (pageNum > 0)
			{
				pageNum--;
				Refresh();
			}
		}

		if (GUILayout.Button("Next\n>", GUILayout.Width(60), GUILayout.Height(40)))
		{
			if (pageNum < pageMax)
			{
				pageNum++;
				Refresh();
			}
		}

		if (GUILayout.Button("End\n>>", GUILayout.Width(60), GUILayout.Height(40)))
		{
			if (pageNum != pageMax)
			{
				pageNum = pageMax;
				Refresh();
			}
		}

		EditorGUILayout.EndHorizontal();
		EditorGUILayout.Space();
		EditorGUILayout.Space();
		GUILayout.BeginArea(new Rect(10, 60, 1300, 1100));

		for (int i = (pageNum * colorsPerPage); i < ((pageNum + 1) * colorsPerPage); i++) // -1
		{
			if (i < colors_list.Count)
			{
				int iter = i - pageNum * colorsPerPage;

				GUI.Label(new Rect(
					80 + (iter % colorsPerRow) * (blockWidth + 10), // rect x
					10 + (iter / colorsPerRow) * (blockHeight + 40), // rect y
					blockWidth, // rect w
					blockHeight), // rect h
					//$"{i}:{iter}: " +
					$"{colors_list[i]}");//, guiStyle);

				Rect thisRect = new Rect(
					80 + (iter % colorsPerRow) * (blockWidth + 10), // rect x
					40 + (iter / colorsPerRow) * (blockHeight + 40), // rect y
					blockWidth, // rect w
					blockHeight); // rect h

				GUI.DrawTexture(thisRect, GenerateColorBlock(
					color_dict[colors_list[i]], blockWidth, blockHeight),
					ScaleMode.ScaleToFit, true);
			}
		}
		GUILayout.EndArea();
	}

	Texture2D GenerateColorBlock(Color col, int w, int h)
	{
		Texture2D tex = new Texture2D(w, h);
		tex.filterMode = FilterMode.Point;
		var fillColorArray = tex.GetPixels();

		for (int i = 0; i < fillColorArray.Length; i++)
		{
			fillColorArray[i] = col;
		}

		tex.SetPixels(fillColorArray);
		tex.Apply(true);

		return tex;
	}

	Texture2D GenerateTextureFromColorArray(Color[] caTexture, int w, int h)
	{
		Texture2D tex = new Texture2D(w, h);
		tex.filterMode = FilterMode.Point;
		tex.SetPixels(caTexture);
		tex.Apply(true);
		return tex;
	}

	bool GUIButtonTexture2D(Rect r, Texture2D t)
	{
		GUI.DrawTexture(r, t);
		return GUI.Button(r, "", "");
	}

	public void Refresh()
	{
		Repaint();
	}
}