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