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