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