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