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