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