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