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