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