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