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)(11,12,17,16)(13,18,23,24)(19,20,21,22)(25,26)(27,31)(28,36)(29,33)(30,35)(32,37)(34,38)(39,40)(3,7)(5,8)(10,15)(11,17)(18,24)(19,21)(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)(9,11,14,17)(10,16,15,12)(13,21,23,19)(18,20,24,22)(25,27)(26,31)(28,34)(29,35)(30,33)(32,39)(36,38)(37,40)(1,2)(3,5)(4,6)(7,8)(9,12,14,16)(10,17,15,11)(13,22,23,20)(18,19,24,21)(25,28)(26,32)(27,34)(29,37)(30,38)(31,39)(33,36)(35,40)(9,13,14,23)(10,18,15,24)(11,19,17,21)(12,20,16,22)(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.