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