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