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