As you probably know, Whatever is displayed on the screen is what is printed. Once you get the part of the tree that you want (by setting the options the way you want, and clicking on the correct person), print the tree and download the PDF file. You might have been trying to use the Download link instead of the Print link.
Find the family tree PDF (probably in your downloads folder) and insert it into your Photobook program. Chances are pretty good that your photobook program will insert a PDF file correctly. If it doesn't, there are websites that can convert a PDF into a PNG file.