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