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