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