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