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)(12,20)(13,15)(14,17)(16,21)(19,23)(22,24)(25,26,31,28)(27,32,29,33)(30,34,38,36)(35,39,37,40)(2,3)(6,7)(9,11,14,13)(10,15,17,18)(12,19,21,22)(16,23,20,24)(25,27,31,29)(26,32,28,33)(30,35,38,37)(34,39,36,40)(1,2,5,3)(4,6,8,7)(25,27,31,29)(26,33,28,32)(30,35,38,37)(34,40,36,39)(1,3,5,2)(4,7,8,6)(9,12)(10,16)(11,19)(13,22)(14,21)(15,23)(17,20)(18,24)(25,28,31,26)(27,32,29,33)(30,36,38,34)(35,39,37,40)(1,4,5,8)(2,6,3,7)(9,10)(11,15)(12,16)(13,18)(14,17)(19,23)(20,21)(22,24)(25,29,31,27)(26,32,28,33)(30,37,38,35)(34,39,36,40)(9,13,14,11)(10,15,17,18)(12,19,21,22)(16,24,20,23)(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.