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