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