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