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