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