He was the leader of at-taif which is in the arabian peninsula, you can get a general idea of common arab complexion of the time, most likely light brown or what would be described as olive, leaders of the time in the region were less likely to be very dark skinned ("black") since it is alluded to as uncommon in the hadith regarding "....even if an abissynian slave..." and the comment of the Quraishi when bilal (ra) climbed the Ka'bah at Makkah. It is unlikely to be the Roman "reddish white" due to the fact that he wasn't reported to have been of Roman origin like suhaib is sometimes described as being.
Another method of gaining a very general idea would be to use genealogy software but that wouldn't give you any detailed information about a specific individual.
Google the term "arab" and hit images, you'll find a range of tones to hypothesize from.
aisha the daughter of Abu Bakr assiddeeq is sometimes referred to as being of "pink" complexion so again, you'd have to wonder at how pale her parents would have been while taking into account regional medians in contrast to roman and abbisynian tones.
better still, find the dude and look at him, then you'll probably know for sure, unless he gets pale in cold countries and dark tanned in sunny countries.