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