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