Red most likely ATF leak, yellowish brown, oil.
Trace the transmission cooling lines that run from the transmission to the cooler.
Some busses use the radiator for trans cooling, while others have a separate/remote cooler.
From your pic, it looks like the other leak could be the oil filter. Wipe the body of the filter free of oil, and then try tightening it carefully. You'll need to run it a bit after tightening to see if that was it, or if it helped. If not, more evaluation might be in order.
Good luck, and post up what you find...