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