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