Plots are made with gnuplot, plotmtv, gmv or vtk in combination with Melati. You can use xv to convert the rgb plot format of gmv to other formats sich as postscript. For plotting you can also use matlab and tecplot, which are not free however.
Finally, you can use GID both for preprocessing (mesh generation) and postprocessing (plotting). An extension of GID is available by the name Tochnog-GID, see the homepage. The use of GID is recommended.
With gnuplot you can plot files resulting from control_print_history and control_print_data_versus_data. With plotmtv you can plot files resulting from control_print_plotmtv. With gmv you can plot files resulting from control_print_gmv. Etc.
See the links sections at our homepage where to get these programs.