To view this, simply locate the absence you wish to view within the calendar and click on it. This will open up the booking form, displaying more information on the absence.

Then, click audit trail t the top of the form. This will open a new tab showing the history of the absence. 

NB: You can also locate an absence via a user's profile. Simply navigate to their Holiday tab and click on the view icon corressponding to the absence you wish to view. This will take you to the calendar and highlight the absence to save you time from searching for it.