The oldest known portrait of Jesus, found in Syria and dated to about 235, shows him as a beardless young man of authoritative and dignified bearing. He is depicted dressed in the style of a young philosopher, with close-cropped hair and wearing a tunic.
These early depictions tend to show Jesus conducting acts of miraculous healing.
The first painting of a bearded Jesus doesn't appear until the 4th Century.
Most interesting to me is that there is not a single painted depicting the crucifixion until the 6th Century. Almost like it was important to Christians for at least 500 years after his life and death.