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