How do I ask out a regular customer at my workplace without making her uncomfortable?

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I'm a 21-year-old guy working at a juice shop. There's a regular customer who comes in fairly often, and over the past few weeks I've started to like her.

We haven't had any deep conversations. It's mostly the usual customer-employee interaction, though we've exchanged a few smiles and small talk. I don't know if she's interested or if she's just being friendly.

I don't want to make her uncomfortable because she's a customer, and I also don't want her to feel awkward coming back if she's not interested.

Would it be appropriate to ask her out? If so, what's the least awkward and most respectful way to do it?

My current thought was to wait until she's leaving and simply say something like:

"Hey, I know this is a bit out of the blue, but if you're interested, I'd love to grab a coffee with you sometime. No pressure at all, and if not, that's completely okay."

Would that be the right approach, or should I just leave it alone?