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