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