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