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