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