Once you draw a calendar, you will see a pop-up dialog with options to change the month, year, and starting day for a weekly calendar; the month and year for a monthly calendar; and the starting month and year for a yearly calendar.  You will also see a button for "more options".  Click this to change the way your calendar looks.... this controls things such as the size of the month title, the size and placement of numbers, how the days of the week are displayed and so on.  At any time you can come back to this dialog box by right clicking on your calendar and choosing edit calendar or simply by double clicking on a calendar.

By selecting a calendar and hitting Alt-Enter, you are able to change the fill, font, line color and style, text color, and shadows. If you want to make several calendars with the same format properties, but for different months, you can create one calendar, then apply the formatting you want.  Then ctrl-drag to duplicate it as many times as you wish.  Then double click to change the calendar to the month desired.  You can also use the format painter to apply formatting from one calendar to another.