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