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