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