Create an epic street art painting of a mythical creature emerging from a cosmic portal, surrounded by vibrant colors and intricate details.

Visualize an awe-inspiring street art painting showcasing a mythical beast stepping out from an otherworldly portal. The creature is engulfed in a burst of radiant colors signifying its aura. The background expresses an opulence of intricate patterns enhancing the overall surreal ambiance. The paintwork includes hues which are so vibrant that they seem to burst off the wall, adding an element of magic and mystery to the scene.