You can have more than one calendar. Create one for work and another for your free time.
Select Calendar.
Select
> Calendars >
.
Write a name, then set a colour code for the calendar.
Set the visibility for the calendar. When a calendar is hidden, the calendar events and reminders are not shown in different calendar views or on the home screen.
Select
.
In the Calendars view, select the calendar you want to change.
Change the name, colour, and visibility.
Select
.
When adding a calendar event, select
and the calendar.
Fill in the fields, then select Save.
Colour codes show which calendar an event belongs to.