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