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