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