In my NOS Whelen 5200-PA there are one red, two purple and two white cables.
The white cables are for the cruise light, the red is for positive power (12 Volt) and the purple ones for ground and hi/lo switching.
Red and purple seems to be standard colours for Whelen due to the fact that most Whelen strobes I have use these colours.
Maybe the cables of yours are customer installed.
Have you checked what the colour are on the cables that goes from the power supply. I assume that the cables you see are the ones that goes out of the light.
There is a AMP connector between the power supply and the connection cables so there are probably different colours.