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)(11,20)(12,18)(13,14)(15,17)(16,21)(19,23)(22,24)(1,3,5,8)(2,6,4,7)(9,11)(10,16)(12,13)(14,24)(15,21)(17,20)(18,19)(22,23)(25,26)(27,32)(28,29)(30,31)(33,38)(34,40)(35,37)(36,39)(1,2,5,4)(3,6,8,7)(10,17)(11,21)(12,22)(14,19)(26,31)(29,38)(32,39)(35,40)(1,2,5,4)(3,6,8,7)(9,12,15,22)(10,18,17,24)(11,13,21,23)(14,16,19,20)(25,27)(26,32)(28,37)(29,35)(30,36)(31,39)(33,34)(38,40)(1,2,5,4)(3,6,8,7)(9,13)(10,19)(11,12)(14,17)(15,23)(16,18)(20,24)(21,22)(25,28,30,33)(26,29,31,38)(27,34,36,37)(32,40,39,35)(1,4,5,2)(3,7,8,6)(9,14,15,19)(10,13,17,23)(11,18,21,24)(12,16,22,20)(25,29)(26,33)(27,35)(28,31)(30,38)(32,34)(36,40)(37,39)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.