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