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