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