One vertex per element, one color per generator, with an edge from x to x·s.
(6,8)(9,10,15,20)(11,21,23,36)(12,24,28,39)(13,16,29,18)(14,30,26,19)(17,32,35,27)(22,34,37,31)(25,33,40,38)(1,2,3,4)(6,8)(9,11,15,23)(10,16,20,18)(12,25,28,40)(13,14,29,26)(17,33,35,38)(19,36,30,21)(22,32,37,27)(24,31,39,34)(2,4)(5,6,7,8)(9,12,26,32,15,28,14,27)(10,17,30,39,20,35,19,24)(11,22,29,40,23,37,13,25)(16,31,36,38,18,34,21,33)(9,13,14,23,15,29,26,11)(10,18,19,36,20,16,30,21)(12,25,27,37,28,40,32,22)(17,34,24,38,35,31,39,33)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.