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