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