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