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