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