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