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