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