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