You can view a colleague's calendar by accessing the "Calendar" page, from the left side menu. From there, click the drop-down menu where your name is displayed, and then select the colleague whose calendar you want to see.
In order to view the calendar of more than one user, you need to be the administrator of your network. In the Calendar page, swich from "My calendar" to "Scheduler".
From there, you can select as many users as you want to, and you can use the same filters you find in the calendar (tags, type of task, monthly and weekly view, etc.) to have a better view of your colleagues' tasks.
You have the possibility to drag and drop the tasks to reschedule them at a different date/time, to assign them to a different team member, or to add an extra assignee to that intervention.