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