How long has she been doing this? Has it stopped yet? It's possible that she did accidentally aspirate some water into her lungs, so the best thing to do is to set-up a ramp using a small board or hard-cover book, something that you can put underneath her basking and
UVB light on a downward slope, and put her on it with her head pointing down the ramp, so that the water can run out of her chest, and the heat from her basking bulb can help to dry it up. If you can bump the temps up 5-10 degrees by lowering the basking bulb an inch or two towards her that would also help, keep her like this for a day or two, until she's breathing normally again.
It's quite possible that she may develop an Upper Respiratory Infection from this, so you need to keep a close eye on her, and if she starts coughing or wheezing, if you hear any "clicking" noises when she breathes, or if you start seeing any excess mucous around her mouth (if you see mucous "strings" when she opens her mouth), and/or if she stops eating or becomes lethargic and starts sleeping a lot, then she'll need to see a Reptile Vet and have a culture/swab taken from her throat/nostrils to diagnose the infection and so she can be put on the appropriate medication. Hopefully this won't happen, but you need to keep a close eye on her for the next week or so.