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)(19,24)(20,23)(21,22)(29,37)(33,38)(34,39)(36,40) involution — undirected(1,2,5,6)(3,7,4,8)(9,11)(10,16)(12,20)(13,15)(14,21)(17,18)(19,22)(23,24)(25,26)(27,28)(29,33)(30,31)(32,35)(34,36)(37,38)(39,40)(1,3,5,4)(2,7,6,8)(10,17)(11,13)(12,19)(21,23)(26,31)(28,35)(33,38)(36,40)(1,3,5,4)(2,7,6,8)(9,12,15,19)(10,14,17,24)(11,20,13,22)(16,21,18,23)(25,27,30,32)(26,28,31,35)(29,34,37,39)(33,36,38,40)(1,4,5,3)(2,8,6,7)(9,13,15,11)(10,18,17,16)(12,22,19,20)(14,23,24,21)(25,28)(26,32)(27,31)(29,36)(30,35)(33,39)(34,38)(37,40)(9,14)(10,19)(11,21)(12,17)(13,23)(15,24)(16,22)(18,20)(25,29)(26,33)(27,34)(28,36)(30,37)(31,38)(32,39)(35,40) 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.