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