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