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