I heard this song, Must Be Santa, several years ago, and I thought that it was such a fun song that I had my class learn it. I made a book of the song. The lyrics are not mine, and the pictures are "coloring pages" I Googled with certain phrases. I just put them together to make this book. Each full page contains the same page of the book, so it saves you paper.
Here is a link to the song on YouTube: https://www.youtube.com/watch?v=42_vCV2_gf0
Your kids will love it! Enjoy and Merry Christmas!