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)(11,16)(12,13)(14,19)(15,17)(18,24)(20,21)(22,23)(25,26,30,32)(27,35,36,31)(28,39,38,33)(29,34,37,40)(1,2)(3,6)(4,7)(5,8)(9,11,15,14)(10,16,17,19)(12,20,18,22)(13,21,24,23)(25,27,30,36)(26,31,32,35)(28,37,38,29)(33,40,39,34)(1,3,5,4)(2,6,8,7)(10,17)(12,18)(16,19)(20,22)(26,32)(27,36)(28,38)(34,40)(9,12,15,18)(10,13,17,24)(11,20,14,22)(16,21,19,23)(25,26)(27,31)(28,33)(29,34)(30,32)(35,36)(37,40)(38,39)(1,3,5,4)(2,6,8,7)(9,13)(10,18)(11,21)(12,17)(14,23)(15,24)(16,22)(19,20)(25,28)(26,33)(27,37)(29,36)(30,38)(31,40)(32,39)(34,35)(1,4,5,3)(2,7,8,6)(9,14,15,11)(10,19,17,16)(12,22,18,20)(13,23,24,21)(25,29,30,37)(26,34,32,40)(27,38,36,28)(31,39,35,33)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.