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