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