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