I don't have a book recommendation, but I do have a dvd recommendation... Baby signing Time dvds 1, 2, 3, & 4. They do wonders!! She goes through all of the basic words and words that are most important. Sometimes it's easier for ASD kids to sign instead of try to get the word out. I still sign with my teenage daughter, especially when she's got her headphones on. It's more helpful than you would think, and easy.

I had the same problem with mine at that age. I found that the books by Roger Hargreaves, Little Miss, worked great if I read them really fast at first. Then we were able to go a little slower as time went by. Those books worked great for starting out. Then it proceeded to Pete the Cat series.

I am in the same boat… I found Ms.Rachel’s speech videos help and they enjoy it. Maybe give it a try. Books- I was advised to read normal children’s books, but my son struggles to lay still and listen and just wants to tear the pages- so Ms.Rachel’s videos helps a lot.
I hope this helps.
Good luck and know it takes time, but gets easier.♥️