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