Remote KeyPad with Buttons

Hi everyone I’m in a bit of a pickle. I’m trying to make a remote security keypad in unity. So basically it displays a gameObejct with 10 different buttons that represents 0-9 digits. Once push the button will turn red, which will symbolize that it is pushed. I’m having trouble setting this up can some one help please? I started but then I don’t know where to go. And yes it is in CSharp.

using UnityEngine;
using System.Collections;
using System.Collections.Generic;
public class KeyPad : MonoBehaviour
{
   public float distance = 25.0f;
   public GameObject buttonZero;//Number Zero Button for the KeyPad

   void Update () 
   {
    if(Input.GetMouseButtonDown(0))
    {
        Ray rayOrigin = Camera.main.ScreenPointToRay(Input.mousePosition); 
        RaycastHit hitInfo; 

        if (Physics.Raycast(rayOrigin, out hitInfo, distance))
        {
            Debug.Log ("0");//Just to let me know its hitting the object

            if (hitInfo.rigidbody != null) 
                hitInfo.transform.buttonZero.renderer.material.color = Color.red;

        }
    }
   }
}

Have you tried changing the input. Edit/Project Settings/Input.