ColorLerper.cs

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

public class ColorLerper : MonoBehaviour {

    public float speed = 1.0f;
    public Color startColor;
    public Color endColor;
    public bool repeatable = false;
    float startTime;

	// Use this for initialization
	void Start () {
        startTime = Time.time;
	}
	
	// Update is called once per frame
	void Update () {
        if (!repeatable)
        {
            float t = (Time.time - startTime) * speed;
            GetComponent<Renderer>().material.color = Color.Lerp(startColor, endColor, t);
        }
        else
        {
            float t = (Mathf.Sin(Time.time - startTime) * speed);
			GetComponent<Renderer>().material.color = Color.Lerp(startColor, endColor, t);
        }
	}
}