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