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