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