Zooming in on the map can help if you know the approximate location. Clicking on the symbol will bring up the name of the cemetery with a link to the Find a Grave cemetery page.
While looking at the main cemetery page it is easy to see if the cemetery has been mapped or not. There is a tab in the upper left hand corner of the page that says "Map", which will give the GPS coordinates and a map. Do note that some of the smaller cemeteries may be wrong, either because of a typo at some point, because someone is guessing the location, or the information was pulled from another source that was wrong. The USGS maps used information from a variety sources, including Names in Stone, and I have found a couple of cemeteries that were off by a few streets. For the most part though I have found the maps to be very useful and spot on in locating cemeteries.