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