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