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