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