He doesn't specifically talk about graphs, but he says his usual workflow is sketch in pencil, then draw, then scan and postprocess: http://www.maa.org/Mathhor

He doesn't specifically talk about graphs, but he says his usual workflow is sketch in pencil, then draw, then scan and postprocess: http://www.maa.org/Mathhorizons/MH-Sep2012_XKCD.html http://www.maa.org/Mathhorizons/MH-Sep2012_XKCD.html