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