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