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