Hans-Karl,
Yes, before 1812, the Sumsky Regiment's dolman was sandy-yellow with dark blue collar and cuffs. Since 1812, the dolman was grey with red collar and cuffs.

http://www.kulichki.com/gusary/istoriya/otkrytki/vypusk2/sumy.jpg

The hussars on the book cover are in 1812 Akhtyrsky Regiment uniform dress: brown dolman with yellow collar and cuffs.

http://www.kulichki.com/gusary/istoriya/otkrytki/vypusk2/ahtyr.jpg

Best wishes,
Alexander