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)(11,17)(12,16)(13,15)(14,19)(18,24)(20,22)(21,23)(25,26,29,31)(27,33,35,28)(30,32,38,40)(34,36,39,37)(9,11,13,19)(10,14,15,17)(12,20,21,18)(16,24,23,22)(26,31)(27,34)(28,36)(30,38)(33,37)(35,39)(2,5)(6,8)(25,27,29,35)(26,28,31,33)(30,39,38,34)(32,36,40,37)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,23)(22,24)(26,31)(27,35)(32,40)(34,39)(9,12,13,21)(10,16,15,23)(11,18,19,20)(14,22,17,24)(25,28)(26,27)(29,33)(30,36)(31,35)(32,39)(34,40)(37,38)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.