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