Don
Your best bet is to get Windsock Datafile No.67 AEG C.IV by Albatros.
The Datafile shows one scheme in a very dark green/brown, but notes that actual colors are not certain. Undersurfaces are shown a light blue.
Also Internet Modeler Oct/2000 has a similar scheme by Bob Pearson - somewhat lighter than the Datafile. See:
http://www.internetmodeler.com/2000/Oct2000
Go to the Galleria on WWI German 2 Seaters at the bottom of the index page.
Cliff