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