That’s perfectly solveable with math. Each grid square can take 10 colors, so there are 10^100 possibilities. That’s about 330 bits of entropy, or equivalent to a 51 character password. That’s gross overkill if the underlying cryptosystem isn’t broken, but insufficient if it is (depending on the details).

Cryptography routinely deals with much, much larger numbers than what you’re suggesting (e.g. any RSA key), and even those get broken occasionally.