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