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