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