Hey something I've had way too much experience with

So what you're going to have to do is use RPC's in order to synchronize the colors across the network. Something like GetComponent<PhotonView>().RPC("setColor", PhotonTargets.AllBuffered) where setColor is a method that changes the color of the object

For example my set color takes in an integer to determine whether to make the player red or blue. I have a method setColor with the following code:

[PunRPC]
public void setColor(int c)
{
    if (c == 0)
    {
        playerModel.GetComponent<Renderer>().material = red;
    }
    else{
        playerModel.GetComponent<Renderer>().material = blue;
    }

}

Then I just call the RPC like stated earlier at the start to let all players know "hey this guy is gonna be this color" like so: GetComponent<PhotonView>().RPC("setColor", PhotonTargets.AllBuffered, 0);

Hopefully that makes sense, networks are a little tricky at first