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