In figure

Figures, as graphical elements, use the same terminology as other graphical items: in a painting, in a photograph, in your web browser.

Source
Source: http://www.usingenglish.com/forum/threads/11216-quot-On-Figure-quot-or-quot-in-Figure-quot
http://english.stackexchange.com/questions/27689/usage-of-in-figure-vs-on-figure
http://www.answers.com/Q/Is_it_correct_to_say_Shown_in_figure_or_shown_on_figure