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