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