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