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