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