  Cachazo and Skinner have recently conjectured a new formula for the complete
tree-level S-matrix of N = 8 supergravity. The formula is an integral over the
moduli space of rational curves in supertwistor space, and remarkably,
manifests the full permutation symmetry of graviton scattering amplitudes. We
check that the formula is parity invariance and reproduces the correct
universal soft behaviour of graviton amplitudes.
