Colours in iCal

I use iCal Ver 5.0.2 on an iMac. When creating new calendars and assigning a different colour to each, how do I get iCal to use strong bold positive colours like red, blue, green rather than the insipid washed out standard colours available? The iMac display is using the default colour profile without any modifications.

If iCal cant be made to do this, is there another Mac compatible calendering system available that will?