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