I responded to your request on Steelnavy as well Ian.
S-100 Class boats only wore Schnellbootweiss, an off white light gray color, with dark gray decks, and black or dark gray below the waterline.
There is a single photogrpahic example of an S-100 class boat wearing camo, but this photo has not been made public as of yet.
www.prinzeugen.com is the premier site to visit for information on the S-boats.
Regards,
Jeff Herne
Modelwarships.com