MaterialColorChanger.cs

using UnityEngine;
using System.Collections;

public class MaterialColorChanger : MonoBehaviour
{
	void Update()
	{
		if (Input.GetKeyDown(KeyCode.R))
		{
			GetComponent<Renderer> ().material.color = Color.red;
		}
		if (Input.GetKeyDown(KeyCode.G))
		{
			GetComponent<Renderer>().material.color = Color.green;
		}
		if (Input.GetKeyDown(KeyCode.B))
		{
			GetComponent<Renderer>().material.color = Color.blue;
		}
	}
}