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