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