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