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