red and yellow and pink and green, purple and yellow and blue
But seriously, the Pembas are a cool range of colours though not from Malawi. Kandangos would probably be suitable as well and show a nice range of colours throughout quite a few phenotypes. Also the OB Peacocks, although a man made species, have a pretty sweet range of colours too. In your size tank you should be able to provide hiding places for a wicked community of cichlids!