You could ask your supervisor if some mistake has been made in the schedule, and whether it would be possible to change your hours.
If that doesn’t work, ask your pastor (ahead of time) for a dispensation (removing the obligation to attend Mass). This should be done before the fact, not after you have missed Mass.
I wouldn’t recommend doing this on a regular basis, however. If that is the only Mass available to you all weekend, you need to come to some understanding with your employer so that your spiritual life does not suffer. Or find a different job with better hours. Or ask the chaplain if there is anyone who regularly goes to Mass off-campus who could pick you up.
