Hey man, I guess you've heard it before, fooling around at work may not be such a good idea... I speak from experience

Getting down to business, my advice would be to meet her in a social setting without any co-workers present, that would greatly reduce your chances. Make your interest known, there is no point in hiding it, especially in this situation. If she wants to meet you, that's fine, if not, don't push it... You have a good DHV in front of her with your job and all, she may already be attracted to you...
How to invite her... talk about some fun stuff tht you do in your spare time and when she's interested, ask her to join you... I have taken girls horseback riding, to the shooting range, for ATV rides in the forest and even flying light aircraft... If you get the adrenaline running, it will increase your chances with her... Hope this helps, Bye!