In my company's employee handbook, the policy says that our workday is 8:30am through 6:00pm, Monday through Friday. We are given an hour for lunch and one flex hour per week. Therefore, our total number of hours per workweek is still 41.5. (We all end up working closer to 50 hours, but the aforementioned is what is written in our handbook). No one receives overtime pay. I'm wondering if there is anything I can do. Is it legal to declare in an employee handbook a workweek that is over 40 hours in CA without any mention of overtime pay?

You can have a mandated workweek of 60 hours and it would be legal. Nothing in the law dictates what your employer can require as a workweek.

Regardless of the length of your workweek, however, if you are non-exempt you must receive overtime whenever you work over 40 hours in a week. If you are exempt, you NEVER have to receive overtime. It really is that simple.

You have not given us any clues as to whether you are exempt or non-exempt, though.