You need to first download the MadAnalysis package from a MadGraph Download page, untar it in the MadGraph5_vx_x_x directory and run "make". Then download Topdrawer (link provided on the same page) and place it in the directory "td" under MadGraph5_vx_x_x. The generate_events script looks for the MadAnalysis executable at ../MadAnalysis/plot_events (seen from the process directory), and for the TopDrawer executable at ../td/td. Now generate_events will automatically run plot generation on your events.
-- Main.JohanAlwall - 2011-07-19