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)(11,18)(12,22)(13,16)(14,17)(15,20)(19,24)(21,23)(25,26,29,33)(27,35,37,31)(28,34,30,32)(36,40,38,39)(2,5)(6,8)(9,10)(11,18)(12,16)(13,22)(14,17)(15,19)(20,24)(21,23)(25,27)(26,31)(28,36)(29,37)(30,38)(32,40)(33,35)(34,39) involution — undirected(1,3)(2,6)(4,7)(5,8)(9,11,14,21)(10,15,17,24)(12,19,13,20)(16,23,22,18)(26,32)(28,30)(31,39)(33,34)(35,40)(36,38)(3,7)(6,8)(9,12,14,13)(10,16,17,22)(11,19,21,20)(15,23,24,18)(25,28,29,30)(26,32,33,34)(27,36,37,38)(31,40,35,39)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.