The Master Frog painting (titled Master Frog) is, as the name suggests, a portrait painting of Master Frog himself. Its artist is unknown. It currently stands on display within the Jade Palace's Hall of Warriors.
This painting of Master Frog shows the master perched on a lily pad next to a lotus flower in the middle of a small body of water (presumably a pond). The painting's caption says:
Beware his Musical Mayhem attack.