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)(27,33,35,40)(28,29,36,37)(31,38,39,34)(1,3,4,7)(2,5,6,8)(9,11)(10,14)(12,18)(13,19)(15,22)(16,21)(17,23)(20,24)(25,27,29,34,30,35,37,38)(26,31,28,33,32,39,36,40)(2,6)(5,8)(10,15)(11,18)(16,17)(19,24)(26,32)(28,36)(31,39)(33,40) involution — undirected(10,16)(13,20)(14,21)(15,17)(19,24)(22,23)(25,28,29,32,30,36,37,26)(27,33,34,39,35,40,38,31)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.