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