Patience, young paduan ...
Where do those wires go ? What game is plugged in to the harness ?
Wire colours are not always (indeed, when there is question, most often are not) indicative of anything.
I would expect one of the wires to be a positive voltage for power, one to be a ground return for power, one to be a common ground and one to be a coin up switch.
Perhaps one of our UK friends can shed more light (WTF would somebody use a different 56-pin standard from JAMMA ?), but tracking the four wires back to their sources (presumably on a 56-pin harness) should reveal the answers that you are looking for.
http://www.hardwarebook.info/Electrocoin