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