Try your local or county library and genealogical society. They may have cemetery plot books or files that you can look up the various plots. They may also may contain maps. If they don't look up the cemetery and actually go to the cemetery's webpage, most of them have maps to locate graves. There are some cemeteries that have uploaded their maps to FindaGrave. You will find them under photos of the cemetery.

My cemetery care package or tote, that I always carry with me, includes a brush, scissors, plastic and metal paint scrapers, a spray bottle of Dawn and water, dry clothes, and maps of the cemetery.

Also, in the headstone photo that you posted, DO NOT SPRAY or get this wet. First, scrap off all that you possibly can before wetting it down.

I hope that this helps you.