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