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