I usually export graphs from python in SVG format, which means I can then edit them with Inkscape to make nice, combination figures for publication, tweak the colours and so on. I expect I could probably edit in Adobe Illustrator, too.
A python tip to ensure your fonts work when exporting to SVG is to do this:
import matplotlib.pyplot as plt
# This line means that when you open the svg in Inkscape, the fonts will 'just work'