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