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