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