change the color of different players

hi, im making a multiplayer game and i want to make it so in the minimap each player see’s him self as a different color than the other player (or atleast sees only himself in the minimap).
i have attached to the player prefab an arrow that only the minimap camera can see, and to this arrow i attached the following script:

using UnityEngine;
using UnityEngine.Networking;

public class arrow : NetworkBehaviour {

    void Update()
    {
        if (isLocalPlayer)
        {
            Material material = new Material(Shader.Find("Standard"));
        }
    }
}

the script doesnt work and when there are multiple players connected each player sees all the arrows in his minimap in the same color.
please help me and let me know what i did wrong, keep in mind that my english and programming arent very good so if you could change the script yourself and give me a working version itll be great, altho every help will be appreciated, thanks.

Try using :

public GameObject player;

 if (isLocalPlayer)
  {
        player.GetComponent<Renderer>().material.color = red;
        //choose whatever color you need.
  }

If all the players are using the same material, editing one players material will in turn edit all of them (because they are using the same instance of a material). You need to edit the sprite renderer color or whatever you are using instead. Or i guess give them all a different material but thats sketchy. Capisce?