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)(25,26,30,33)(27,31,38,34)(28,32,39,29)(35,37,40,36)(9,11,13,19)(10,14,16,17)(12,18,20,24)(15,21,22,23)(25,27)(26,31)(28,35)(29,36)(30,38)(32,37)(33,34)(39,40)(1,3,5,4)(2,6,7,8)(9,12,13,20)(10,15,16,22)(11,18,19,24)(14,21,17,23)(25,28,30,39)(26,32,33,29)(27,34,38,31)(35,37,40,36)(10,16)(14,17)(15,22)(21,23)(25,28)(26,32)(27,35)(29,33)(30,39)(31,37)(34,36)(38,40) involution — undirected(1,4,5,3)(2,6,7,8)(11,19)(14,17)(18,24)(21,23)(27,36)(28,39)(29,32)(31,35)(34,40)(37,38)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.