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