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