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