How's this for a spooky coincidence? Orang-utans are orange in colour, but the orang bit of their name has absolutely nothing to do with the colour orange.
The word orang-utan derives from the Malay/Indonesian words orang, meaning person, and hutan meaning forest; orang-utans were people of the forest. Years before Darwin, the wise folks of the Malay Archepelago knew a close relative when they saw one.
The word orange, on the other hand, has a very complex derivation, given on Answers.com as follows:
Middle English, from Old French pume orenge, translation and alteration (influenced by Orenge, Orange, a town in France) of Old Italian melarancio: mela, fruit + arancio, orange tree (alteration of Arabic naranj, from Persian narang, from Sanskrit narangah?, possibly of Dravidian origin).
In other words, absolutely nothing to do with orang-utans. Like I said, spooky coincidence.
I worry about this sort of thing a lot.