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