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