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