Make touch buttons transparent

I have made a game that uses touch buttons, but I don’t want the buttons to be visible once the game starts and I can’t seem to find any way to do it. I’ve made a simple script that sets the object with the 3 UI images in too inactive but this means the buttons no longer work. Can anyone help?

using System.Collections;
using System.Collections.Generic;
using UnityEngine;

public class startGame : MonoBehaviour {

	public GameObject touchUI;
	public CanvasGroup touch;
	public GameObject startUI;

	void Start(){

		touchUI.SetActive (true);
		startUI.SetActive (true);
		Time.timeScale = (0.0f);
	}


	public void startGameClick(){
		
		touchUI.SetActive (false);
		startUI.SetActive (false);
		Time.timeScale = (1.0f);
	}
}

Thanks Calum

Put a Canvas Group on each of them and you can control CanvasGroup.alpha…

put a material on it, then control the transparancy of that material with a script or a shader.