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