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