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