Reddit mentions of Sweary Coloring Book: Coloring Books For Adults Featuring Stress Relieving Filthy Swear Words, cute kitten, adorable puppies and colorful flies (Swear Coloring Book) (Volume 1)

Just to show you how non-religious I am, my first thought at your suggestion of an adult coloring book was something like this.

However, once my brain kicked into gear and I realized what you meant, I instantly thought that's a great idea. Her gift of the Bible to you was her way of sharing something personal that likely brings her peace and comfort. If there's not something equally personal to you that would interest her, an adult coloring book would hit all the right notes.

I'm thinking specifically of mandala coloring books. Those are (I'm told - I keep meaning to try it, but haven't gotten around to it yet) things that encourage clearing the mind and becoming tranquil. And while I can't speak for her, I know if someone gave me something with that hint of whimsy, I'd go nuts over it.

I think your idea is fabulous, so much so that I'm having trouble coming up with something that would be even half as good.