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