Konsole may support more than 8 colors but if your TERM environment is set wrong then the OS won't know it can. If you bypass the OS and print the color escape sequences directly (as the script is doing, naughtily[1]) then it might just work.

[1] The proper way is to use terminfo to output the escape sequences for you. See http://perldoc.perl.org/Term/Cap.html for how to do this with standard Perl. EDIT: I can't get this to work—Seems Perl has poor terminfo support. :-( "tput setaf 10" is the correct way from sh.

Yes, this change was reverted. + Now there is --ascii option to view the graph with some ascii characters instead of ANSI colors

Yes, apparently it does the same thing as gnome-terminal, which does not advertise its support for 256 colors.