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