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