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