  The superconducting properties of layered materials can be controlled by
thinning, stacking, and twisting, demanding investigation of electronic states
by spectroscopic means at the nanometer scale. Here, we reveal the spatial
variations of the electronic states in heterostructures of the superconducting
monolayer NbSe$_2$/graphene using spectroscopic-imaging scanning tunneling
microscopy. The NbSe$_2$ monolayer grown by molecular beam epitaxy is naturally
twisted with respect to the graphene substrate and exhibits interference
patterns of Bogoliubov quasiparticles twisted with respect to the NbSe$_2$ and
graphene lattices. We find that the twisted interference patterns originate
from a sextet of regions in momentum space where the Fermi surfaces of NbSe$_2$
and graphene overlap. The Fermi surface overlap is sensitive to the twist
angle, providing a knob to tune superconductivity.
