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)(27,32)(28,33)(29,37)(30,31)(34,39)(35,36)(38,40) involution — undirected(1,3,6,7)(2,4,5,8)(11,17)(15,21)(18,23)(22,24)(26,31)(28,32)(34,37)(36,38)(1,2,6,5)(3,8,7,4)(10,14)(15,21)(16,19)(22,24)(26,31)(27,33)(34,37)(35,40)(1,4)(2,7)(3,5)(6,8)(9,10)(11,15)(12,16)(13,14)(17,21)(18,22)(19,20)(23,24)(25,27,30,33)(26,32,31,28)(29,35,39,40)(34,38,37,36)(1,4)(2,3)(5,7)(6,8)(9,11,13,17)(10,15,14,21)(12,18,20,23)(16,22,19,24)(25,28,30,32)(26,33,31,27)(29,38,39,36)(34,35,37,40)(1,5,6,2)(3,8,7,4)(9,12,13,20)(10,16,14,19)(11,18,17,23)(15,22,21,24)(25,29,30,39)(26,34,31,37)(27,35,33,40)(28,36,32,38)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.