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