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