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)(11,20)(12,17)(13,18)(14,28)(15,19)(16,23)(21,34)(22,30)(24,35)(25,31)(26,33)(27,32)(29,36)(37,39)(38,40)(9,11,13,22,15,24,14,23)(10,16,28,35,19,30,18,20)(12,21,27,38,26,37,25,36)(17,29,31,39,33,40,32,34)(2,4) involution — undirected(5,7,8,6)(9,12,15,26)(10,17,19,33)(11,21,24,37)(13,27,14,25)(16,29,30,40)(18,32,28,31)(20,34,35,39)(22,38,23,36)(9,13,15,14)(10,18,19,28)(11,22,24,23)(12,25,26,27)(16,20,30,35)(17,31,33,32)(21,36,37,38)(29,39,40,34)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.