I last visited the Panteón General or the Main Cemetery of Oaxaca City in 2016. It is well maintained, clean and has sidewalks. If you are enjoy visiting graveyards, this is a place for you. The graveyard is now full so if you want to get buried there, you are probably out of luck.
If you are in Oaxaca during the celebration of the Día de Muertos or Day of the Dead, you might want to visit this place. The place gets filled up with tourist and bus tours during this time. For the rest of the year, it is quiet and a nice place to visit.
You could walk there from the Zócalo but I think taking a taxi there would be best, there is a lot of traffic in the area.
This is pinkish marble tomb (below) is my favorite.
This grave marker (below) is the most original I saw there.
Photos taken by Marc Wilkinson. I, the copyright holder, hereby publish these photos under the following license: Creative Commons Attribution-ShareAlike 3.0 Unported (CC BY-SA 3.0).