Is it appropriate to copy a drawing from a book in my master thesis? I would like to know if it is appropriate to copy a drawing from a book (specifically a directed graph) and develop my theory on that drawing? It is sure that I am going to make a reference for that drawing.

Note: The author of that book I intend to copy the drawing develops his theory based on that figure, but I am going to approach everything it matters more deeply.
Well, to my eye this is a good case of improving the state of the art, of course citing appropiately your sources. It is the same as quoting from a book.

On the other hand, if the publisher is especially nitpicking, maybe you could just use a software editor to re-create the drawing (still sourcing!) instead of using the "edited" drawing from a book.