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