How can students increase their employability upon graduation?

1, Employability should be prepared way before graduation and usually is not something can be built in last minute right before or on graduation. e.g. going for good internships with valuable experience to train your communication and problem solving skills.
2. If you are already graduating, my suggestion is to put in more effort in understanding the industry and company you want to apply to, spend some time to customize your resume according to their needs and rehearse your interviews.
3. And most importantly, practise make perfect, do not hesitate to go to all interview invitations and apply to as many relevant jobs you are interested as possible. (if you are unsure what you want exactly). This is to help you to understand the job more when you attend more interviews.

Be confident that you will do a great job in the workplace. That energy alone can get you any job you want.