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