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