I was wrong; it's actually a children's storybook.... printed on coloring book paper..... bound and sized like a coloring book..... with line art illustrations that I suppose you could color.....
Published in 1965, the untitled story is rather innocuous, and has no relation to any episode aired. In short, some never-to-be-seen-again friend gets Samantha worried that Darrin will lose interest in her if she doesn't get a hobby.... (yeah, like that whole twitching your nose and stuff appears thing is so mundane)
The line art work (by Beverly Edwards) is pretty good (better than the typical coloring book renderings). However, it's only "on model" for the three main characters.
Take a look below when Gladys Kravitz does her usual Peeping Tom routine.
Who, or what is that?!? This hideous Gladys has no resemblance to either of the two actresses that played, and especially not Alice Pearce, who was Gladys in the first three seasons before her death in 1966. Here's the appropriate pic for comparison:
When Endora shows up, you can see the artist has captured Agnes Moorehead's bemused expression perfectly.
But then, look at poor Aunt Clara and portly Larry Tate!
My only guess is that there was something in the licensing agreement or the actors' contracts that didn't allow the supporting characters to match up.
A quick Google search shows that Beverly Edwards illustrated other children's books, most notably one of Disney's Mary Poppins Golden Books.
As for budding author Ellen Lenhart, Amazon only shows that she did Portrait of Skipper (which sounds like an ABC Afterschool Special), and something called Astronut and the Flying Bus. I'm thinking she may have peaked here with Bewitched.
And -- spoiler -- Samantha decides being a housewife is all she needs....