If such a particle as a graviton exists then it may be the effects on spacetime itself rather than on matter directly that is the principle of gravitation. If the graviton's effects on time dilation and length contraction are considered these may induce both planetary spin and elliptical orbits.
This effect would be produced by the declining intensities away from a mass of both time dilation and length contraction. The drag on an orbiting body would be more nearer the orbited mass. This difference may seem inconsequential but may be just enough to induce rotation in an orbiting body and slow its momentum away from the central mass to produce orbits of varying shapes
This implies that the length contraction and time dilation produced near to light speed has a direct connection to the graviton. In some way the increase in energy may also increase the gravitational strength of the moving body. This may indicate a link between collapsed masses and those approaching light speed.
The starting point for any investigation is the equation.
T= T0/SQRT(1-(2GM/Rc^2))
For the length contraction component I will start here:
http://www.newtonphysics.on.ca/gravity/Combining the effects of both will be required.