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