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