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