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