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