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