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