Enum change visible in editor?

I have an object with an enum that has {Red,Green,Blue}

And depending on which enum is picked, the color of the object changes.

It works fine ingame, the object changes color and all.

The problem is that in the editor no matter what enum I pick, the color will not change.

In the update I simply did if enum = green, then material = green.

I tried to use [ExecuteInEditMode] but it didn't seem to work.

I really need to be able to see the changing color in the editor itself, otherwise building the level becomes hard.

using UnityEngine;
using System.Collections;

public class colorChanger : MonoBehaviour {

    public enum _color
    { 
        red,
        green,
        blue
    }
    public _color Colors = _color.red;
    // Use this for initialization
    void Start () {

    }

    // Update is called once per frame
    void Update () {
        if (Colors == _color.blue)
            renderer.material.color = Color.blue;

    }
}

Execute in edit mode had to go to very top for it to work, fixed