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