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