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