Why does Zeus always look a certain way in video games? The easy answer is: We have an extraordinary amount of depictions of Zeus in classical art that folks draw on. Why do we stick to that design? Because, re: SMT, when we redesign Zeus too much, it becomes very difficult to ID

Why are most Zeus depictions gold and blue?
Because Gold and Blue pop. It's the whole logo bible of having orange and blue on movie posters. Zeus is notably identified by the color purple in mythology, but American culture makes a vast majority of these products, and we're weird.

No purple. Make him Gold and lightning is blue so make him blue. Blue and gold clothes. Great.
So you end up with a homogenized Zeus, that is kinda universal with tweaks here and there. Yeah we have outliers, but Zeus is a greek dude with muscles, a beard and lightning bolts.

And because Americans are so inexorably hung up on the idea of gender identifiers and color contrasts for rivals and all that super sentai-ass patterning, Hera ends up always wearing some shade of red. Hera should be in blue, but we made Zeus blue! Make her red, nobody reads.

HESTIA - Red
ARES - Dark Red
ARTEMIS - Silver
HEPHAESTUS - Orange(Gold-Red)
HERA - Blue
POSEIDON - Deep Blue
ATHENA - Light Blue
APHRODITE - Pearl
APOLLO - White
HERMES - Gold
ZEUS - Purple
DEMETER - Green

Even in HADES how often do you see this color setup? Ever?

The easiest ones for Americans are Hades is Dark Red because blood is red and war is red but black is spooky so we make all depictions of Ares black and red.
We don't make a distinction between "death" and "the underworld", and folks don't know Hades was the god of money

So they hone in on death! And death is black and blood is read so guess what Hades is black and red too and not gold the way he should be!
A lot of this stuff is ingrained through ignorance and repetition and making something easy to understand.

As an example from the entire other side of the continent, none of the colors of the Armies in Dynasty Warriors are correct. The Blue/Red/Green thing is just so it's easy to identify who is whomst at a glance. It's a design trick.