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