Although the old man depiction of him is the most prevalent and modern, more monstrous forms of Matarajin-sama still made it into present times.
The first image depicts Daikokuten-sama in a form resembling Mahakala. This image is actually cropped, in the original he's surrounded by the Seven Matrikas, one of Matarajin-sama's possible namesakes. He's holding the skin of a demonic elephant he defeated, which a friend of mine suggested might have evolved into Daikokuten-sama's sack he carries around on his back, which symbolizes wealth and prosperity.
The being in the middle image is known as Sanmen Daikokuten, a depiction of his with three head (head of Daikokuten-sama, Bishamonten-sama and Benzaiten-sama) their six hands are holding items their single form is associated with.
The final image is a modern depiction of Matarajin-sama, or as she's locally called, Madarajin. She very obviously resembles the early depictions of Daikokuten-sama, and notably is depicted as a female deity.