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