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