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