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