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