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