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)(11,12)(13,16)(14,15)(17,18,21,20)(19,22,24,23)(25,26,30,33)(27,34,31,28)(29,37,38,32)(35,36,39,40)(1,3,5,4)(2,6,8,7)(9,11)(10,13)(12,14)(15,16)(17,19,21,24)(18,22,20,23)(27,31)(28,34)(35,39)(36,40)(9,12,15,13)(10,16,14,11)(17,19)(18,22)(20,23)(21,24)(25,27,30,31)(26,28,33,34)(29,35,38,39)(32,36,37,40)(1,2)(3,6)(4,7)(5,8)(9,13,15,12)(10,16,14,11)(17,18,21,20)(19,22,24,23)(25,28)(26,31)(27,33)(29,36)(30,34)(32,39)(35,37)(38,40)(1,4,5,3)(2,7,8,6)(9,14,15,10)(11,12,16,13)(17,20,21,18)(19,23,24,22)(25,29,30,38)(26,32,33,37)(27,35,31,39)(28,36,34,40)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.