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