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)(25,26,31,39,30,35,29,34)(27,36,37,32,28,33,38,40)(1,2)(3,7)(4,5)(6,8)(9,11)(10,14)(12,18)(13,19)(15,22)(16,17)(20,23)(21,24) involution — undirected(2,5)(6,7)(25,27,30,28)(26,32,35,40)(29,37,31,38)(33,39,36,34)(9,12,13,21)(10,15,16,20)(11,18,19,24)(14,22,17,23)(25,28,30,27)(26,33,35,36)(29,37,31,38)(32,39,40,34)(1,3,4,8)(2,6,5,7)(11,19)(14,17)(18,24)(22,23)(25,29,30,31)(26,34,35,39)(27,37,28,38)(32,33,40,36)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.