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