Reddit mentions of The Vince Guaraldi Collection: Piano (Artist Transcriptions)

You might be hard-pressed to find a free copy since Hal Leonard is very jealous of their IP and are known to sweep the web for copyright infringement, but you can purchase this book which apparently has a full transcription of Vince's "O Tannenbaum" and other tunes.

edit: I browsed the WorldCat interlibrary loan catalog and it seems there's only one copy somewhere in South America so it looks like you either need to buy the book, transcribe the tune yourself, hire someone else to do so, wait forever for an interlibrary loan or perhaps get lucky from somewhere else but it looks like buying the book is probably the easiest way to get the sheet music.

Here you go. I think if you like it this much, it's worth $15 to you to get a book with this and eight other pieces by Guaraldi. Only fair to pay for what you use, man.

I'mma just leave this here.

You could do worse than learning some Vince Guaraldi chops. This book has a lot of good material that range in difficulty from "easy" to "kinda hard". This one is a more "serious" book that includes more involved transcriptions of some of the famous pieces ("Linus and Lucy", "Christmas time is here" and "O Tanenbaum" are much more developed in this one) and it includes "Cast your fate to the wind".

The entire Vince Guaraldi book (also linked upthread) only has the one error that I've noticed compared to the original recordings (it is in "Christmas Time Is Here"). The book does not include the bass lines, however, only the piano parts. The book includes "Hark, the Herald", "O Tannenbaum", "Christmas Time Is Here", "Greensleeves", and "Linus and Lucy". These are all transcribed from the versions you hear on radio and TV. The book also includes "Cast Your Fate to the Wind" and 3 other songs by Guaraldi. This book is essential if you want to play these songs authentically.

edit:added link