The final deadline for filing for graduation is usually shortly after the beginning of the last semester of coursework. The specific date for this deadline can be found here. It is best to file early - during the semester before your last one - so that you will learn of any deficiencies in time to correct them.
The necessary forms are available either in the Computer Science Department office or at Admissions and Records.
You will need to complete a Graduation Application Form. On this form you list all courses that you have not completed, whether they are for the major (or minor), for general education, or for general elective units.
Once you have completed the form, bring it to the Computer Science office (Darwin 116) to be signed by your academic advisor and the CS department chair. You may need to leave the form so that it can be reviewed and signed, and retrieve it a day or two later. Then you should take the signed form to Admissions & Records.
Major Contract Addendum
If you file the graduation form and subsequently take courses other than the ones you listed on your form, you must file a Major Contract Addendum form with the changes. This form must be signed by your CS academic advisor and the CS department chair.