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