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