Showing available dates in colour on the calendar graphic for appointments

At the moment a parent has to click on a date to see if there are appointments scheduled because the list onyl shows 5 dates! If we tell them the days/dates then this is fine but if we just want to add dates here and there and not have to email out to parents all the time then they don't know as it isn't obvious because only 5 dates show in the list. Colour coding the available dates on the calander graphic where there are available spaces will help hugely. Thanks