Using the command sims.modify_career_outfit_in_cas I am able to change the clothes of my butler as long as I don't change the shoes. However if I change the shoes it reverts the butlers career outfit back to default butler outfit. Is there anyway to change the shoes my butler wears.

Well, It might be because cheats sometimes don't work with High Graphics, a computer that is old or not vary powerfull (a laptop is one too), or if you plaing with a 8 sim household.

Cheats don't have any correlation with graphics. Otherwise, I don't have an answer to OP's question/problem. I do know the butler outfit is a uniform like any other service Sim, so I'm guessing it's not meant to be changed unless the outfit was totally modded out for all butlers (like someone did with the nanny), because to me the career outfit cheat is meant for the active Sim's career clothes not a NPC's work outfit.