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