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