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