Book recommendations for a PhD supervisor
As a current PhD student thinking about what I'd like a supervisor to be aware of, I can think of a few book recommendations which might be useful. The challenge of doing a PhD which I've noticed is learning how to be efficient and happy in the face of a really different kind of challenge than my previous studies were. These books offer models for that, which might help you make more concrete suggestions to your students when they (inevitably) struggle or at least help you understand them more.  


Deep Work by Cal Newport. A really good advice-filled book about how to get productive, creative work done by relegating distractions and creating the right kind of time/space.
Becoming a Successful Scientist by Craig Loehle. A general book about the sorts of things a scientist in training might need to think about and adapt to.
A book about depression and other mental health struggles, for example Curse of the Strong by Tim Cantopher. This is very likely to be a challenge that your students may face, and knowing a bit about it will make you better equipped to help them.
A book about how to communicate when difficult things are happening. For example, NVC offers an interesting model, as in Nonviolent Communication -- A Language of Life by Marshall Rosenberg.


Hope that's helpful and good luck! And remember that your students can probably tell you a lot about what you need to know to help them if you can get to a place where you can listen and they can share.