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