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