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