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