One of my favorite books for preschool speech therapy is If You See a Kitten by John Butler. The book has helped me elicit sounds and words from some of my most reluctant talkers. Each page has an adorable illustration of an animal along with an exclamation you can say when you see that animal. The kids love yelling “peee-youuu!” when they see the pig, “yuck!” at the slug, and all the other silly exclamations in the book.
The book is great for working on commenting and expanding utterances with kids with autism or language delays. It is also helpful for eliciting sounds with kids who are just starting to communicate.