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