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