Here's a great answer by /u/Dubstripsquads dealing with non-black minorities under Jim Crow. The second part discusses Hispanic Americans, and includes recommended readings on the topic.

Mexican is a nationality, not a race. If you expand it to Hispanics, that's an ethnicity not a race. There are "colored" Mexicans and Hispanics and white Mexicans and Hispanics.

The colored ones would be treated the same as the colored African-Americans. The white ones would be treated the same as white Americans (if they were granted citizenship), otherwise they'd be treated the same way as white immigrants or foreigners from European countries like Spain.