This design is neatly mirrored, meaning that the left side is a flipped copy of the right side and vice versa. If you’re drawing it on a computer, you can make the job easier by drawing only one half of the design, then make the other half by copying it, flipping it and then pasting it into place.
Here’s a quick and easy way to draw an open book:

Begin your book by taking a rectangle that’s a little over twice as wide as it is tall and dividing it in two down the middle. 
Draw another rectangle inside it. This new rectangle should share its top edge with the first rectangle, while the other sides should be a little ways inside it. Try and make the bottom closer to the outer rectangle than the sides.  
Next, draw lines going diagonally upwards and inwards from the corners of the second rectangle. All four lines should be the same length and fairly short.  
Connect the ends of those lines to the line bisecting the rectangles using a curved line. Since these lines define the pages, the bottom lines should be as similar to the top lines as possible.  
Now connect the ends of the lines to each other to finish defining the pages.  
To add bookmarks, draw rectangles that start between the bottom curves and the second rectangle’s bottom side and end a little bit past the bottom side of the bigger rectangle.  
For text, just add some dashes and dots on the pages; don’t try to actually write something there. Erase the unwanted lines to finish the book. 