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)(11,14)(12,13)(15,16)(17,18,21,22)(19,23,24,20)(25,26)(27,31)(28,32)(29,30)(33,38)(34,37)(35,36)(39,40)(3,7)(6,8)(9,11,13,16)(10,14,12,15)(17,19)(18,20)(21,24)(22,23)(26,30)(28,35)(31,37)(33,39)(2,5)(6,8)(10,12)(14,15)(18,22)(20,23)(25,26)(27,31)(28,36)(29,30)(32,35)(33,40)(34,37)(38,39) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,12,13,10)(11,15,16,14)(17,20)(18,19)(21,23)(22,24)(25,27,29,34)(26,31,30,37)(28,33,35,39)(32,38,36,40)(1,3)(2,6)(4,7)(5,8)(9,11)(10,14)(12,15)(13,16)(17,18)(19,20)(21,22)(23,24)(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.