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