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)(11,17)(12,20)(13,15)(14,18)(16,22)(19,23)(21,24)(25,26)(27,33)(28,35)(29,40)(30,37)(31,36)(32,38)(34,39) involution — undirected(2,5)(3,7)(9,11,13,18)(10,14,15,17)(12,21,22,19)(16,24,20,23)(25,27)(26,33)(28,31)(29,30)(32,39)(34,38)(35,36)(37,40)(11,18)(14,17)(19,21)(23,24)(25,28,32,29)(26,34,38,33)(27,30,39,31)(35,37,40,36)(1,3,4,7)(2,6,5,8)(10,15)(14,17)(16,20)(23,24)(25,29,32,28)(26,35,38,40)(27,30,39,31)(33,36,34,37)(2,5)(6,8)(9,12,13,22)(10,16,15,20)(11,19,18,21)(14,23,17,24)(25,30,32,31)(26,36,38,37)(27,28,39,29)(33,40,34,35)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.