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