Yes, this is the fresco in question. At the center top is St. Augustine. At his right hand is the original ΙΧΘΥΣ symbol--a wheel of eight spokes made by combining the 5 letters together (but with a Lunate Sigma--C instead of Σ). This design evidently predates the fish symbol, and it has been argued that the resulting circle was so made because it looks like bread.
At his left hand is a representation of the 10 celestial spheres, and below it the philosophers Socrates, Plato and Aristotle.
Epicurus is on the far right, in maroon or burgundy--you can just make out part of his name. And because I hate to leave the reader with a load of drivel, here's Thoreau;
QuoteI am not sure but I should betake myself in extremities to the liberal divinities of Greece, rather than to my country's God. Jehovah, though with us he has acquired new attributes, is more absolute and unapproachable, but hardly more divine, than Jove. He is not so much of a gentleman, not so gracious and catholic, he does not exert so intimate and genial an influence on nature, as many a god of the Greeks.