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