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