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