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