Go to this link: http://www.airliners.net/
Scroll down to the spot where it says "Choose Aircraft Type"
and then click on the down arrow for a menu of aircraft. Then scroll down to Cessna 180/185 Skywagon, click on the "Show me the Photos" and wait for the first page to load. Once loaded, find the first picture of a 180 and set your cursor on the words "Cessna 180". You will note that they light up. Click on those words and wait a bit while the pictures are sorted by 180's. You will then have 79 pictures of Cessna 180's. You might find one that triggers some color scheme inspiration.

DO the same for the 185's as there are some very sharp colors there too!