  We report the study of ballistic transport in normal
metal/graphene/superconductor junctions in edge-contact geometry. While in the
normal state, we have observed Fabry-P\'{e}rot resonances suggesting that
charge carriers travel ballistically, the superconducting state shows that the
Andreev reflection at the graphene/superconductor interface is affected by
these interferences. Our experimental results in the superconducting state have
been analyzed and explained with a modified Octavio-Tinkham-Blonder-Klapwijk
model taking into account the magnetic pair-breaking effects and the two
different interface transparencies, \textit{i.e.}\,between the normal metal and
graphene, and between graphene and the superconductor. We show that the
transparency of the normal metal/graphene interface strongly varies with doping
at large scale, while it undergoes weaker changes at the
graphene/superconductor interface. When a cavity is formed by the charge
transfer occurring in the vicinity of the contacts, we see that the
transmission probabilities follow the normal state conductance highlighting the
interplay between the Andreev processes and the electronic interferometer.
