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