The black and silver paint scheme is based on two photos of a flight round. One is the same photo that Dave Fitch posted recently, and the other was the same rocket close up on the launch rail. The photos were B&W, but the black was pretty black, and not likely some other dark color. The silver was clearly bare metal, but of course, it's not impossible that it was anodized some color.

As I recall, only four Arcons flew in one series of launches, so it seems likely that they all had that color scheme, and the pretty Arcas-like scheme was probably just for a display/advertising round.