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