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