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)(11,16)(12,15)(13,28)(14,20)(17,24)(18,36)(19,26)(21,35)(22,38)(23,34)(25,30)(27,31)(29,32)(33,40)(37,39) involution — undirected(10,15)(11,21)(12,24)(13,26)(16,32)(17,19)(18,28)(20,31)(22,40)(23,39)(25,29)(27,36)(30,33)(34,38) involution — undirected(2,5)(3,8)(6,7)(9,11,14,23)(10,16,20,34)(12,25,27,40)(13,29,26,22)(15,30,31,33)(17,35,18,37)(19,38,28,32)(21,36,39,24)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.