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)(11,17)(12,15)(13,16)(14,20)(18,22)(19,23)(21,24)(28,35)(32,36)(34,39)(37,40)(1,3,5,8)(2,6,7,4)(9,11,15,13)(10,16,12,17)(14,21,22,19)(18,24,20,23)(25,26)(27,29)(28,36)(30,31)(32,35)(33,38)(34,40)(37,39)(1,3)(2,4)(5,8)(6,7)(10,12)(16,17)(18,20)(23,24)(26,31)(27,33)(32,36)(34,39) involution — undirected(1,4)(2,3)(5,6)(7,8)(9,12,15,10)(11,17,13,16)(14,20,22,18)(19,24,21,23)(25,27,30,33)(26,29,31,38)(28,34,35,39)(32,37,36,40)(9,13,15,11)(10,17,12,16)(14,21,22,19)(18,24,20,23)(25,28,30,35)(26,32,31,36)(27,34,33,39)(29,37,38,40)(9,14,15,22)(10,18,12,20)(11,19,13,21)(16,23,17,24)(25,29)(26,33)(27,31)(28,37)(30,38)(32,39)(34,36)(35,40)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.