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