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