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