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