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