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