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