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