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