Usually, it may not be possible to do fancy graphical operations within a general purpose software like Scilab.  There are tools designed for this purpose, Gnuplot being an example.  Spoken Tutorials on Gnuplot are available here: https://spoken-tutorial.org/tutorial-search/?search_foss=Gnuplot&search_language=English.  Using this software, you can do many more fancy things as well.  Of course, you can continue to use Scilab for computations.