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