One vertex per element, one color per generator, with an edge from x to x·s.
(1,2,11,18,10,19,9,50)(3,20,26,98,27,81,52,80)(4,28,34,68,35,100,51,64)(5,16,53,55,39,74,38,15)(6,40,37,14,44,70,7,45)(8,48,36,73,47,69,43,17)(12,54,79,22,61,90,60,91)(13,32,76,102,67,111,66,31)(21,82,99,124,87,123,86,117)(23,59,89,78,41,112,24,93)(25,57,97,58,95,71,88,121)(29,101,113,62,106,116,84,77)(30,107,109,127,46,75,42,65)(33,72,49,63,110,114,108,126)(56,85,118,103,119,104,122,96)(83,115,105,125,94,128,92,120)(1,3,6,41,8,25,5,22,11,52,37,89,36,88,53,54,10,27,44,23,47,95,39,91,9,26,7,24,43,97,38,90)(2,12,55,57,17,59,14,20,50,79,16,58,69,78,40,98,19,61,15,71,73,112,45,81,18,60,74,121,48,93,70,80)(4,29,102,103,33,105,30,87,51,113,32,104,108,94,42,86,35,106,31,96,110,92,46,21,34,84,111,85,49,83,109,99)(13,62,28,82,65,125,63,56,76,101,68,117,107,115,114,122,67,77,100,123,127,120,126,119,66,116,64,124,75,128,72,118)(1,4)(2,13)(3,21)(5,32)(6,42)(7,46)(8,49)(9,51)(10,35)(11,34)(12,56)(14,68)(15,72)(16,63)(17,75)(18,76)(19,67)(20,77)(22,29)(23,92)(24,94)(25,96)(26,99)(27,87)(28,40)(30,37)(31,38)(33,43)(36,110)(39,111)(41,105)(44,109)(45,64)(47,108)(48,65)(50,66)(52,86)(53,102)(54,84)(55,114)(57,120)(58,115)(59,82)(60,122)(61,119)(62,81)(69,127)(70,100)(71,125)(73,107)(74,126)(78,124)(79,118)(80,116)(83,89)(85,97)(88,104)(90,113)(91,106)(93,117)(95,103)(98,101)(112,123)(121,128) involution — undirectedA 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.