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