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