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