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