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