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