I have an employer that has an employee that works enough hours to meet eligibility for their company health insurance. However, this employee has also been a student at the local college, and had student health plan coverage while enrolled. The student has now graduated, and will be working full-time. The change in hours does not effect her eligibility for health insurance with the employer, but would her loss of coverage as a non-student give her cause to enroll in the employer's health plan now, or is she required to wait until open enrollment?

Any help is greatly appreciated.

IMHO no. That change in status is for covered dependents, when they satisfy or cease to satisfy eligibility requirements.

Based on facts you gave, there is no change in employees eligibility status, so that doesn't offer special enrollment.

Although there may not be a special enrollment option in the plan, the plan may allow the student to enroll with satisfactory evidence of insurability.

Why wouldn't this be HIPAA special enrollment?

From the DOL website:
Under HIPAA, individuals who are otherwise eligible, but had declined health coverage because they had other group health plan or health insurance coverage, must be permitted to enroll in the plan (regardless of any late enrollment provisions) upon “loss of eligibility” for the other coverage or if employer contributions toward the other coverage cease.