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