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