You're best option is probably to check the wiring with a circuit tester to find the correct cables.
Check each cable with all lights off then - with the ignition on - put the car in reverse and check the cables again. The live one will be the reverse.
Or a closer look at the printed circuit board should lead back to the correct pins on the multiplug and then the correct wires.
I suspect one may be a common earth for the light cluster.

 

Thanks for the advice Gonescenile I have managed to wire the camera for any one who is trying this the (black wire is earth) (and the White is live when reverse is selected.)