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