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