I'm looking for vector graphics of each of the mana symbols (normal, hybrid, phyrexian, 2-or-color). Where can I find them?
Slightly Magic has most of them.
This GitHub repository has them. Here is a direct link to the SVG file. The readme says that it uses the ones from the Slightly Magic forum thread that user1873 linked to in their answer, but it also has the colorless mana symbol. This post on the same forum thread has the energy symbol.
I don't see any copyright information, so be careful. They are also protected by trademark.
You can download a font of various magic symbols here. Most vector graphics programs should be able to convert from the font to vectors.