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