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