What do you think about concept map of Buck2? I am just discovering it, and feels like a hodgepodge: language, dependency terminology, common build terminology, specific files of Buck. I find it really hard to understand.
Anyway, I am not aware of any concept map for gradle, but you may find some stuff into docs such as
dependency terminology. Blog is also a good starting point depending of what you want to understand (thinking about
how gradle works serie)