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