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