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