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