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