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