Love the red metal roof! Color really depending on your tastes, and can express your personality. Go to the BYC "Coop" section to browse through the coop pages to get some inspirations. There are some really good "why didn't I think of that" creative color schemes.
For my coop, I chose the colors that are complementary to our house, but subtle enough to blend into the background if seen from the roads. We have a very small lot and don't have a fenced in yard, so a very discrete "curb appeal" was important to us.
Our coop has the same siding and roof colors as the house. The window trim is a similar color as the adjacent plum tree, very close to our house' shutter color as well. I added a highlight green edging color, a dark "chicken poo" color for the interior of the nest box, and a hunter green for the run. Inside the coop is where the "crazy happy" coral color in full brightness, can be seen when the coop door is opened. All in all, plus the white wood primer and the mute green stainless steel primer, I applied 9 different colors in our little coop & run. However, at first glance, you probably won't see all that craziness, just 3 colors at most.
I would suggest that you pick a couple main wall colors that will complement the roof, then find the trim colors that will complement each wall color. Get some samples colors and tape them onto the coop, take a look to see which pallet looks good with the surrounding and looks good to you. Then just go for it! Have fun painting!
