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