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