Though you're definitely on the right board for asking about a name's origin, if you're inquiring about what spellings of
Shayla would be nice aside from
Shayla, then you should go here:
http://www.behindthename.com/bb/list.php?board=baby. The possible exception would be if you want a listing of international variants of a name not listed on BtN.
Personally, I think
Shayla's simply a combination of
Shay and the meaningless modern name suffix
-la. Or it may be a variant of
Sheila, as Behind the Name lists. It could even be a variant of
Shayna via replacing the N with a L. But I'd put my money on the first theory.
Miranda