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