All less you want to get them online and possibly order them, i think you may find something like that on amazon, or if you want to just get them online and print it out, but i doubt if it would be unique as already made with good pictures.
I tried searching for such books but got no positive response from Google and Amazon and it is fine to teach children about bitcoin especially in a comic way but don't we think, we're pushing things too hard on them?
At some points I just think feel most persons who want to introduce bitcoin to their kids are doing so out of regrets and hence wanting to use their kids to correct their mistakes and wanting them be better off in the future then their peers which I don't see as necessary because what will be, will be.
Rather than teaching your kids about bitcoin now, why not get a portfolio for them and help them save, by so doing, when the time is eight fir then to dive into the industry, it might be much more easier for them.
Just my unpopular opinion.