@Pradeep Singh Rao Thanks for reaching out.
If you are using the client creds flow, you should not use the /me endpoint, instead you should use /users/{userID}/calendar/getSchedule
So the resource URL will look something like this :
https://graph.microsoft.com/v1.0/users/2fd17daa-31d6-4a0c-2345-77a01239a3d1/calendar/getSchedule
Also remember the supported method to get the schedule is POST.
So try something like this :