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