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