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)(11,17)(12,22)(13,18)(14,19)(15,16)(20,21)(23,24)(26,31)(27,34)(28,36)(37,39)(2,6)(4,7)(10,16)(13,19)(17,22)(20,23)(25,26,30,31)(27,29,34,32)(28,33,36,38)(35,37,40,39)(1,3,5,8)(2,7,6,4)(9,11,15,12)(10,17,16,22)(13,20,19,23)(14,24,18,21)(25,27,30,34)(26,32,31,29)(28,35,36,40)(33,39,38,37)(1,4)(2,3)(5,7)(6,8)(9,12,15,11)(10,17,16,22)(13,23,19,20)(14,24,18,21)(25,26)(27,32)(28,33)(29,34)(30,31)(35,39)(36,38)(37,40)(1,4)(2,3)(5,7)(6,8)(9,13,15,19)(10,18,16,14)(11,20,12,23)(17,21,22,24)(25,28,30,36)(26,33,31,38)(27,35,34,40)(29,37,32,39)(1,3)(2,4)(5,8)(6,7)(9,14,15,18)(10,19,16,13)(11,21,12,24)(17,20,22,23)(25,29,30,32)(26,34,31,27)(28,37,36,39)(33,40,38,35)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.