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