You need to appeal to her natural sexual drive. Show maturity in your demeanor but confidence in your desire. Straight and to the point would work best here. You are obviously not dating potential, with that being said, you need to appeal to her sexuality.

A straight forward comment is your only shot here. Be mature and keep a straight face. say something like this: ( while looking her straight in the eye, and take talk to her away from anyone else)

"Listen I know I am not your ideal suitor, as I am much younger, but I find you overwhelmingly attractive, I don't normally pursue mature women, but I find my self completely drawn to you. I feel a strong sexual urge towards you. I am not looking to fall in love or anything like that. If you would at least humor me and meet me for a coffee, I would love to show you that I am a worthy of your time.

I promise anything from this point on between you and I will be completely discreet. Life is too short not to follow overwhelming urges. Here is my number, I'll let you think about it. Get back to me regardless. I will respect your decision either way"

( have your number already written down, keep the conversation extremely private and quick, do not show any more attention to her at her place of work once you have dropped your digits on her, she must know you are serious about keeping it discreet)