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