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