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