generate graph from .eps file (preferably using R)
EPS is "Encapsulated PostScript". Its meant for embedding like an image in documents, or sending to printers. You can view it with a PostScript document viewer, and there are free PostScript document viewers for Linux, Windows, and Mac OSs. Ghostview, Evince, etc etc.

So although you can view the graphic once you've got a PostScript document viewer, you cannot load it into R as if you had just plotted it.