ya so i got a used SiR cover the other day and i couldn't even tell it was blue

i guess in the shipping the grease/oil exploded all over the place.
ANYWAY, my friend and i sprayed some simple green on it, and it seems like it did a good job except it's still not as blue as it should be. there are still parts that have grease on it too
is there any recomendation of another degreaser i can use besides simple green? something perhaps a bit stronger?