I had two swatches for each colour, and glued them back to back to form a book layout. I decided on this style rather than flash card style (with the same colour on the front and back of one card). Then I found some patterned paper to make a front and back "cover".
To make them into a book I punched two holes in each card and threaded two rings through (I used the ones usually used for keyrings).
Then I decorated each page with colour themed stickers and letters.
F seemed to really enjoy the format - it wasn't just a regular book and it contained bright but simple images and colours that appealed.