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