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