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