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