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