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