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