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