Given the diversity of the "CTO" role in terms of responsibilities and scale - what you should be reading will vary depending on your current size, composition, industry and your own personal experience level.
One I find no trouble recommending regardless of these however is High Output Management by Andy Grove (of Intel). Not a new book, but chalk full of what I consider absolute truths when it comes to optimizing middle management (which is predominantly your role as a CTO, once the org reaches 50+ people and your direct reports all have direct reports). The fact it is still very relevant to organizational challenges today when it was written 40 years ago is a testament to this. It is a shame there are so few books that focus on this very-ignored (and honestly largest) segment of management and arguably where you get the most traction as a company.
I've yet to meet two CTOs that share the same skillset or strengths, or who work in the same org structure.
I would recommend doing some executive courses and trainings (with our other execs) to learn some common language and techniques/methodologies around team management and execution - this has been the thing which helped me most in embracing a CTO role (even one with other CTOs from separate business units reporting into). It is ironic but the best blend for a high level CTO is actually people and organizational skills moreso than pure technical aptitude. You need to be able to fact check your people and ask the right technical questions and understand the fundamentals of technical debt and TCO analysis, but honestly you'll be using your people/organizational skills and trying to hire people that know the technology better than you for the most part.