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