Calvary Cemetery is huge! And quite old. The number of historic and locally prominent people buried there is pretty staggering. There have also been a large number of reburials there, by which I mean that quite a few older cemeteries were closed and those interred in them moved to other locations. Calvary seems to have taken in a large proportion of them. That seems to have happened throughout the existence of Calvary.

Have you been to their website? http://archstl.org/cemeteries/content/view/91/233/

At the bottom of the tabs on the left is the Burial Search button. You could see if your relative appears there.

Also, have you looked on Find a Grave.com? There may be a picture of the area your aunt is buried in. If there isn't, I could run over there this weekend and do that for you.