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