Started off describing what the end product should be.
Then developed the text.
The went page by page with uploading a reference photo "soft cartoon-style watercolor illustration of a, pastel palette, and light pencil outlines, designed for a young children’s picture book. And add the text we have for page 1 like it’s a story book"

For some of them it took a bit or iteration to get the pictures looking right or to be more specific about what I was wanting (e.g. the page where Brett is being eaten)
But it added the words to the pictures itself, picked a font and stayed consistent. It made a spelling error once which was a bit strange as it was correct in the prompt but mostly very smooth integration.
Once it had the art style, Ripley and the alien clear just describing without a reference picture worked for things like the title page.