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