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