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