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