How to set color to gameObject respective to below coding?

var prefab : GameObject;
var numberOfObjects = 10;
var radius = 5;

function Start () {
for (var i = 0; i < numberOfObjects; i++) {

   var angle = i * Mathf.PI * 2 / numberOfObjects;
    var pos = Vector3 (Mathf.Cos(angle), 0, Mathf.Sin(angle)) * radius;
    Instantiate(prefab, pos, Quaternion.identity);

}
}

renderer.material.color = yourColor

Assuming you already know all of the colors you need, I would just make an array of Color objects (Color[]) that is equal in length to the number of objects you need.

Set all of these colors (either with an initializer list, a loop, or manually). Then, inside of your loop in Start, you need to change a few things. First off, save the result of Instantiate to a GameObject. To do this, change your line to save it to a GameObject variable.

var myObject : GameObject = Instantiate(prefab, pos, Quaternion.identity);

Essentially, this tells myObject that it is a GameObject, and then sets it to be whatever you just created. After this, simply call

myObject.renderer.material.color = myColorArray*; //myColorArray is the previously mentioned color array*

and you should be all set.