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