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