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