Of course, solar wind produces a magnetic field and pyrolytic graphite is indeed a diamagnetic material. When the magnetic field exerts a force on the pyrolytic graphite spacecraft, the particles of the solar wind will be deflected by the Lorentz force. Pretty much like what happens in a magnetosphere. It wouldn't propel the spacecraft, the particles will just flow around the spacecraft and may give it a slight nudge here and there. But, in any case, it would certainly not be possible for solar wind to "propel" the spacecraft, since, all the particles will be moving in random directions with all the possible speeds.
I highly recommend you to read these articles (since it is a topic which is still being researched upon):
By using article (1), I could establish that a spacecraft made up of pyrolytic graphite will work the exact same way as in a magnetosphere-solar wind interaction