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