I wouldn't have described graph theory that way. But category theory seeks to formalise and generalise mathematics itself. Another popular branch of mathematics that does this is set theory, which you may have been thinking of rather than graph theory.
Set theory is generally taught before category theory at universities. "Simpler" is very subjective, but set theory is often seen as more intuitive because some of the concepts start getting taught much earlier in school.
Set theory is generally taught before category theory at universities. "Simpler" is very subjective, but set theory is often seen as more intuitive because some of the concepts start getting taught much earlier in school.