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