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