The first set of lyrics posted are what I've always heard, and are what's in the sheet music. That troubleome word is spelled "cayuse." The sheet music has quite a few more chord changes in some parts, but they aren't necessarily critical. I would suggest to at least go to Gm for the works "trees" and "senses."

Somewhere--I don't recall if was on Mudcat or elsewhere--I read about the authorship of this song. What I recall is that Cole Porter did some significant, though not extensive, reworking of the original poem or song. He wanted to give the other fellow co-writing credit, but his record label or publisher or whatever nixed the idea. In recent years there has been more frank acknowledgement of its not being solely Porter's work.

I'm thinking there may have been a recent thread on this song, perhaps with most of the additional chords (I'm pretty sure I posted them). That might also have been where I read about the evolution of the song.