a kenyan sand boa would be a great choice because they come inin few bright colours and they dont get very large. their only draw back is they spend 96% of their time under their substrate cause they are burrowers. they are great snakes though.
here is mine, Lucifer
https://ball-pythons.net/gallery/fil...0855_thumb.jpg
http://www.ball-pythons.net/gallery/...imageuser=8834