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