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