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