One way of doing it would be as follows: using the name of the post to determine how it displays.
Firstly, open page.php and "Save As" it to single-book.php.
Secondly, find "the loop", i.e. where your page.php has its while... statement.
You can then use code similar to the following to differentiate styles between different books:
<?php while (have_posts()) : the_post(); ?>
<?php global $post; ?>
<?php if ( stristr($post->post_name, "Book 1") ) : ?>
<?php /* do something for your first book here */
<div class="post" id="post-<?php the_ID(); ?>">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
<div class="entry">
<?php the_content('Continue reading »'); ?>
</div>
<?php else if ( stristr($post->post_name, "Book 2") ) : ?>
<?php /* do something different for your second book */
<div class="post" id="post-<?php the_ID(); ?>">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
<div class="entry">
<?php the_content('Continue reading »'); ?>
</div>
<?php else : ?>
<?php /* do something different for the rest of the books... */
<div class="post" id="post-<?php the_ID(); ?>">
<h2><a href="<?php the_permalink() ?>" rel="bookmark" title="Permanent Link to <?php the_title(); ?>"><?php the_title(); ?></a></h2>
<div class="entry">
<?php the_content('Continue reading »'); ?>
</div>
<?php endif; ?>
<?php endwhile; ?>
The stristr PHP function checks to see if the second parameter (here string "Book 1") exists in the first parameter (here string $post->post_name). It also differentiates for "Book 2". Obviously you can add as many of those as you like and change the text accordingly.