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