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)(25,26,30,35)(27,36,33,32)(28,38,39,37)(29,34,31,40)(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)(26,32)(28,34)(29,38)(30,33)(31,37)(35,36)(39,40)(11,17)(14,20)(18,23)(21,24)(25,28,29,32,30,39,31,36)(26,33,40,37,35,27,34,38)(1,4,5,3)(2,6,7,8)(9,12)(10,15)(11,18)(13,19)(14,21)(16,22)(17,23)(20,24)(25,29,30,31)(26,34,35,40)(27,37,33,38)(28,32,39,36)(12,19)(15,22)(18,23)(21,24)(25,29,30,31)(26,34,35,40)(27,38,33,37)(28,36,39,32)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.