Reddit reviews Angry Octopus

A couple kids books that might be helpful to read and discuss together:

Moody Cow Meditates, which features the brilliant "mind jar", also called a calm-down jar or feelings jar. See these instructions (and some cool variations) for making your own. The idea is she can shake up the jar/bottle to get her anger out, and then sit quietly watching the glitter settle as her thoughts settle.

Anh's Anger models using deep breathing to help big feelings get smaller. The sequel looks pretty good too though I haven't read it. They feature a younger child though (unlike Moody Cow, who appears to be school-aged) so may be a bit less appealing to her.

Angry Octopus is the picture book version of a guided meditation for kids that takes them through a progressive relaxation exercise. There's also a coloring book companion now which looks awesome!

What to Do When Your Temper Flares is more of a guidebook for slightly older kids, based on a cognitive-behavioral techniques; Hot Stuff to Help Kids Chill Out looks similar. You might also check out a workbook like this.

Hope some of that is helpful, best of luck!