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