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