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