A large part of my master's thesis (~25%) is essentially a summary of one book. How to cite correctly and in a tastefull manner?
Overriding answer: ask your advisor.

In expository work like this, what I've usually seen done is that you start the section with a note saying something like "The material in this section is primarily drawn from  Handbook of Reticulated Splines by P. Smith [47]."  After that, you don't bother to decorate every sentence with "[47]" or "as  Smith states", except where you feel it is particularly important for clarity or the reader's convenience (e.g. you want to quote Smith's exact words, or point the reader to something on a specific page of the book, or you want to discuss Smith's approach in contrast to someone else's).

But again, ask your advisor in case they have some other ideas as to how you should handle it.