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