standard colours for HU would be:-
positive = red
ground = black
as for speakers, look for pairs of colour but 1 would have black line, the other would not have black line (eg. 2 grey wires, 1 grey wire has got a black line on it, the other grey wire no black like).
After pairing up all these, u would still have a few remaining wires which would be for:-
1. Accessory wire (positive only when the key is turned)
2. Remote wire (for amp, not all models have this), when HU on, positive signal
3. Power antenna (for those antenna with motor), when radio on, Positive signal
4. Other etc wires like handbrake signal etc...
hope this helps...