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)(19,23)(21,24)(25,26)(27,31)(28,36)(29,30)(32,38)(33,35)(34,40)(37,39)(1,3)(2,6)(4,8)(5,7)(10,13)(14,16)(17,18,20,22)(19,21,23,24)(26,29)(27,33)(32,36)(34,37)(1,4,7,6)(2,3,8,5)(9,10,12,13)(11,14,15,16)(25,27,30,33)(26,31,29,35)(28,37,38,34)(32,40,36,39)(1,5,7,3)(2,4,8,6)(17,19)(18,21)(20,23)(22,24)(25,28)(26,32)(27,34)(29,36)(30,38)(31,39)(33,37)(35,40)(1,6,7,4)(2,3,8,5)(9,11)(10,14)(12,15)(13,16)(25,29,30,26)(27,35,33,31)(28,36,38,32)(34,40,37,39)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.