How to make RANDOM COLOR on shader

I use Retro Pixel Unity Asset Store - The Best Assets for Game Making shader

I use 8 colors, and I want to change them color at random every time

I wrote this;

public Color color0 = Color.black;
public Color color1 = Color.white;
public Color color2 = new Color(Random.value, Random.value, Random.value, 1.0f);
public Color color3 = new Color(Random.value, Random.value, Random.value, 1.0f);
public Color color4 = new Color(Random.value, Random.value, Random.value, 1.0f);
public Color color5 = new Color(Random.value, Random.value, Random.value, 1.0f);
public Color color6 = new Color(Random.value, Random.value, Random.value, 1.0f);
public Color color7 = new Color(Random.value, Random.value, Random.value, 1.0f);

but not changed colors every time

How should I do

The follow script will change the colors every time.

using UnityEngine;
using System.Collections;
using AlpacaSound;

public class TestRetroPixel : MonoBehaviour
{
    public RetroPixel retroPixel;
    
    // Use this for initialization
    void Start ()
    {
        GetRandomColors();
    }
    
    public void GetRandomColors ()
    {
        if (retroPixel != null)
        {
            for (int i = 0; i < 7; i++)
            {
                switch (i)
                {
                    case 0:
                        retroPixel.color0 = Color.black;
                        break;
                    case 1:
                        retroPixel.color1 = Color.white;
                        break;
                    case 2:
                        retroPixel.color2 = GetRandomColor();
                        break;
                    case 3:
                        retroPixel.color3 = GetRandomColor();
                        break;
                    case 4:
                        retroPixel.color4 = GetRandomColor();
                        break;
                    case 5:
                        retroPixel.color5 = GetRandomColor();
                        break;
                    case 6:
                        retroPixel.color6 = GetRandomColor();
                        break;
                    case 7:
                        retroPixel.color7 = GetRandomColor();
                        break;
                }
            }
        }
    }
    
    Color GetRandomColor ()
    {
        Color color = Color.black;

        while ((color == Color.black) || (color == Color.white))
        {
            color = new Color(Random.Range(0.0f, 1.0f), Random.Range(0.0f, 1.0f), Random.Range(0.0f, 1.0f));
        }
        return color;
    }
}

Attached is a [79390-testretropixel.zip|79390] that tests RetroPixels.