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