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