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