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