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