Documents you should send:
1. Invitation form college (usually internal student office issues one, this is required to prove that you are in-fact graduating) send the original.
2. Your current transcript (unofficial should do)
3. Any awards or Honors you have received as a student (to show that you are a good student, copies should do)


Source: my self and friends have done the same,

Thanks NightElf. I wonder if photocopy works for transcript.

it should, because you have a letter from your Uni stating that you are in good academic standing - i think that alone should be sufficient, copy of transcript is like a back up.