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