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