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