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