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