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