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