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