One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,5)(6,8)(9,10,15,20,22,21,31,38,14,19,32,24,16,11,13,18)(12,25,28,40,39,23,26,37,27,17,33,35,29,36,30,34)(2,5)(6,7)(9,11,22,19,14,21,16,10)(12,23,29,17,27,36,39,25)(13,18,32,20,31,38,15,24)(26,34,33,35,30,37,28,40)(1,3,4,8)(2,6,5,7)(9,12,14,27)(10,17,19,25)(11,23,21,36)(13,30,31,26)(15,28,32,33)(16,29,22,39)(18,37,38,34)(20,35,24,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.