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