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