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