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