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