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