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