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