Well "CD" if I may be so informal, you have not chosen a subject that lends itself to much colour variation.
I know of two colour profiles:
Fighters 1914-19 by Ken Munson published by Blandford, a small book first published in 1968 - I suppose it was reasonable bearing in mind the state of research at that time - at least he shows camels and Se5s etc in brown and not that awful green that people used to think British machines were finished in. The FB5 is depicted with clear doped linen flying surfaces, fin, and the fuselage sides, and the fuselage top decking, nose and underparts (which I assume to be plywood) are shown in brown. Fuselage cockade between pilot and observer/gunner, wing cockades in usual places, and blue/white/red fin. There is a letter "S" in a circle on the fin - I don't know the significance of this, but there are certainly period photographs showing this mark.
The second is The Encyclopedia of the Worlds Combat Aircraft by Bill Gunston and published by Salamander.
This is a bit of a pile em in and hope nobody notices the mistakes type of book, probably a childrens book if the truth be told. The FB5 is mostly depiced the same as above, except that the plywood fuselage parts look to be some sort of silvery blue - hard to tell. No letter "S" on the fin.
Now, if you get a copy of Jack Bruce's "The Aeroplanes of the Royal Flying Corps" by Putnams, you will see some period photographs where the fuselage wooden parts appear dark and some where they appear to just be clear doped. What is interesting is that he shows a photograph of one machine with a Union Flag instaed of the later cockades - that might me a bit different, it appears to be clear dope all over as well, so no arguements about the colour!
I think we would all like to see a photograph posted of your model - how about it?