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