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