  We present a theoretical analysis of the relaxation cascade of a photoexcited
electron in graphene in the presence of RPA screened electron-electron
interaction. We calculate the relaxation rate of high energy electrons and the
jump-size distribution of the random walk constituting the cascade which
exhibits fat tails. We find that the statistics of the entire cascade are
described by L\'evy flights with constant drift instead of standard
drift-diffusion in energy space. The L\'evy flight manifests nontrivial scaling
relations of the fluctuations in the cascade time, which is related to the
problem of the first passage time of L\'evy processes. Furthermore we determine
the transient differential transmission of graphene after an excitation by a
laser pulse taking into account the fractional kinetics of the relaxation
dynamics.
