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