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