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