OS X Mavericks :: How To Assign Colors To Calendar Groups

Trying to set up calendar in Mavericks 10.9.3.  The defaults are Blue = Home, Green = Work, Purple = Holidays  and Grey = Birthdays.. until you uncheck some and they disappear. 

all up and adding them ourselves.But when adding my own groups,  I'd like them in different colors to make them stand out. However, they're all showing up as grey.  I can't seem to find anywhere where I can set up my own colors.   I wish Apple weren't getting so controlling. I know many of you want everything to synch up but........not everyone uses the calendar for work or even wants to sync it with anything else.  

The Calendar app used to be simple and easy and you could set it up however you wanted. Doesn't appear so now and very group the same grey color, isn't very useful!  I'd get rid of "Home" too but it's the only thing that isn't grey besides Holidays-- since I eliminated "Work".   I don't know what "Home" is.  Since "Holiday" is purple, I want "Medical Appts." in Red.  I want other things in other colors.