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