  For chaotic scattering on quantum graphs, the semiclassical approximation is
exact. We use this fact and employ supersymmetry, the colour-flavour
transformation, and the saddle-point approximation to calculate the exact
expression for the lowest and asymptotic expressions in the Ericson regime for
all higher correlation functions of the scattering matrix. Our results agree
with those available from the random-matrix approach to chaotic scattering. We
conjecture that our results hold universally for quantum-chaotic scattering.
