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