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