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