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