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