To display a technicians availability go to the calendar, click on the gear icon in the top right hand corner, and then check the "Show Availability" box. Lastly, don't forget to save your changes :)
The technician's availability will display according to their scheduling rules as a shaded background on their calendar.
Month View Calendar - Example
Week View Calendar - Example
Note: The availability for each technician only shows when you are viewing a single user's calendar. It will not display if you have multiple users selected.